1. Field of the Invention
The present invention relates generally to a motor drive, and more particularly to a drive with heat dissipation and energy-saving function.
2. Description of the Related Art
In general, in order to promote working efficiency or achieve some specific work objects, a motor needs to have different operation patterns in accordance with the requirements of users. Currently, a motor is generally used in cooperation with a motor drive. A user can adjust the set parameters of the motor drive according to different working requirements to control the operation mode of the motor, for example, to start or stop the motor. However, when the motor abruptly accelerates or decelerates or in the case that the motor drive is under a high-load condition, the temperature of the motor drive will rise. In this case, it is necessary to additionally mount a predetermined number of cooling fans for lowering the temperature so as to protect the motor drive.
When the motor drive gives a stop command to the motor, the motor will not immediately stop operating, but will gradually brake and decelerate. At this time, the coils of the motor will still continuously intersect the magnetic field to create induced electric potential and produce regenerative current passing through the circuit. In case that the regenerative current fed back to the motor drive exceeds a value bearable by the motor drive, the electronic components of the motor drive will be damaged.
Currently, for overcoming the above problem of the conventional technique, in design of electrical control, the speed and acceleration/deceleration specification required by a user are previously calculated in detail and then a regenerative resistor with proper ohm value is additionally connected with the rectification circuit in the motor drive. The regenerative current is conducted to the regenerative resistor and consumed so as to protect the motor drive. In other words, the regenerative resistor can consume the energy generated when the motor abruptly accelerates or decelerates so as to prevent the energy from being directly absorbed by the capacitors of the motor drive. This can minimize the possibility of failure of the motor drive.
The above conventional device is able to achieve heat dissipation effect and effectively consume the regenerative current for protecting the motor drive. However, the conventional device still has the following shortcomings as follows:    1. It is necessary to additionally provide multiple cooling fans for lowering the temperature of the motor drive. This leads to waste of energy.    2. In design of electric control box, it is necessary to additionally reserve a space for placing the regenerative resistor. As a result, the usable room is reduced.